Infill

Infill density

The infill density defines the amount of plastic used on the inside of the print. A higher infill density means that there is more plastic on the inside of your print, leading to a stronger object. An infill density around 20% is used for models with a visual purpose, higher densities can be used for end-use parts.

The model on the left has a higher infill density than the model on the right.

Infill line distance

Instead of setting the infill density as a percentage, it’s also possible to set the line distance. This determines the distance between each infill line, which has the same effect as changing the infill density.

Infill pattern

Cura allows you to change the pattern of the printed infill structure, which could be beneficial in some cases. There are 8 options available:

Grid: A grid shaped infill, with lines in both diagonal directions on each layer.

Lines: Creates a grid shiped infill, printing in one diagonal direction per layer.

Triangles: Creates a triangular shaped infill pattern.

Cubic: A 3D infill of tilted cubes.

Tetrahedral: A 3D infill of pyramid shapes.

Concentric: The infill prints from the outside towards the center of the model. This way infill lines won’t be visible through the walls of the print.

Concentric 3D : The infill prints from the outside towards the center of the model, with an incline over the entire print.

Infill line directions

The infill lins usually print in a 45° angle. At this angle, both the X- and Y-motor work together, to obtain maximum acceleration and jerk on the layer without losing quality. If for some reason the lines have to be printed in a different direction, you can set it here. 0° is vertical and 90° is horizontal. For example: [0,90] results in a horizontal - vertical top/bottom pattern.

Infill overlap (percentage)

With this setting you can control the amount of overlap between the infill and walls. It can be set as a percentage or a true value. A higher value usually results in better bonding between the infill and walls. On the other hand it might also reduce the (visual) quality of the print, as a too high value could lead to over extrusion. The default value in Cura will in most cases be sufficient.

A visualization of the infill overlap and wipe distance.

Skin overlap (percentage)

The skin overlap works equally to the infill overlap, which is described in detail above. It can be set as a percentage or a true value. The skin overlap influences all top and bottom layers in a print.

Infill wipe distance

This setting tells the printer to stop extruding at the end of printing the infill, [x] mm before it starts printing the walls. The printer will then still ooze a little bit of plastic, due to the pressure in the nozzle. By stopping the extrusion early, over extrusion on the shell of the object is minimized. See the image above.

Infill layer thickness

Since the layer height of the infill is not important for visual quality, you can decide use thicker layers on the infill, so the print time is reduced. When you adjust this setting, always ensure that it is a multiple of the layer height (otherwise Cura will round it to a multiple of the layer height).

This means that you can for example print with an infill thickness 0.2 mm while the layer height is 0.1 mm. The printer will then first print the walls for 2 layers, after which it will print 1 thicker infill layer.

Gradual infill steps

Gradual infill lowers the amount of infill used, by decreasing the infill percentage on lower layers. Every gradual infill step divides the infill percentage by a factor two. Example: Gradual infill steps = 2 and infill = 20% --> Infill = 20% for the top 5mm, infill = 10% for the rest of the print.

Gradual infill step height

Gradual infill step height is the height at which the infill should be reduced as calculated from the top layers. This way the top layers can be closed easily, without the use of much infill throughout the print.

Infill before walls

With this setting enabled, infill will be printed before the walls. This results in better overhangs because the walls will stick to the already printed infill. Nonetheless, printing in this order can also have a disadvantage: If the infill is printed before the walls, there’s a chance that the infill is visible through the walls, resulting in a less smooth surface finish.

Minimum infill area

This setting allows filling small areas on a single layer to be printed with skin instead of infill. Take a flat roof with a chimney for example: the chimney is thin and fragile and will be printed completely solid, with skin.

Expand skins into infill

This setting expands the skin horizontally, where normally infill would be printed. Doing this with a small amount allows protruding model elements to have better adhesion to the rest of the model. A large flat surface with a small protruding pipe in the z-direction will have a stronger base, making it sturdier.

Skin expand distance

Set the distance of the expansion fo the skin here. A bigger value ends up in longer, but sturdier prints. A lower value increases strength just a little.

Maximum skin angle for expansion

Since skin areas are present throughout the model, it would not make sense to expand all these areas. Instead, only the areas below the angle given here will be expanded. This way, flat surfaces with protruding elements are strengthened, while leaving the rest of the model as is.